Monday, October 17, 2011 at 2:42 pm.

Apple’s iBooks app rides the iPhone 4S wave, Amazon Kindle app doesn’t

Here’s one more chart showing some interesting iPhone App Store mechanics over the past week.

Apple updated its iBooks app last Tuesday ahead of the iOS 5 and iPhone 4S launches, and featured it in the App Store. Over the week, as Apple’s big launches rolled out, the iBooks app soared in the App Store rankings, peaking on Saturday at no. 12, as tabulated by AppAnnie.

But Amazon’s Kindle app didn’t budge, hovering around the 150 mark, where it tends to stick around. (Kindle even dropped to no. 4 in the Books category, down from its usual no. 2 spot. iBooks is always no. 1.)

iBooks Kindle chart

One bizarre thing I noticed: If you search for “books” on the iPhone App Store, the Kindle app doesn’t show up in search results. (iBooks is the sixth result, after some other e-books apps, such as Nook, Kobo, etc.) I’m not sure if that is Amazon’s fault (perhaps bad App Store SEO) or Apple’s fault (payback for the Kindle Fire?), but I wouldn’t be surprised it it had some effect on sales.

Update: Matthew Panzarino and Shawn Blanc note on Twitter that Apple is prompting iBooks installs during the iOS 5 upgrade and activation processes. This didn’t happen to me, perhaps because I already had it installed on my old iPhone and iPad. But that could be another explanation for the rise in iBooks downloads.

Also: Here’s how Apple is forcing a worse user experience on its customers